Muc-1, integrin, and osteopontin expression during the implantation cascade in sheep.
ABSTRACT The extracellular matrix protein osteopontin (OPN) is a component of histotroph that increases in uterine flushings from pregnant ewes during the peri-implantation period and is localized on the apical surfaces of the uterine luminal epithelium (LE) and conceptus trophectoderm (Tr). The potential involvement of OPN in the implantation adhesion cascade in sheep was investigated by examining temporal, spatial, and potential functional relationships between OPN, Muc-1, and integrin subunits during the estrous cycle and early pregnancy. Immunoreactive Muc-1 was highly expressed at the apical surfaces of uterine luminal (LE) and glandular epithelium (GE) in both cycling and pregnant ewes but was decreased dramatically on LE by Day 9 and was nearly undetectable by Day 17 of pregnancy when intimate contact between LE and Tr begins. In contrast, integrin subunits alpha(v), alpha(4), alpha(5), beta(1), beta(3), and beta(5) were constitutively expressed on conceptus Tr and at the apical surface of uterine LE and GE in both cyclic and early pregnant ewes. The apical expression of these subunits could contribute to the apical assembly of several OPN receptors including the alpha(v)beta(3), alpha(v)beta(1), alpha(v)beta(5), alpha(4)beta(1), and alpha(5)beta(1) heterodimers on endometrial LE and GE, and conceptus Tr in sheep. Functional analysis of potential OPN interactions with conceptus and endometrial integrins was performed on LE and Tr cells in vitro using beads coated with OPN, poly-L-lysine, or recombinant OPN in which the Arg-Gly-Asp sequence was replaced with RGE or RAD. Transmembrane accumulation of talin or alpha-actinin at the apical surface of uterine LE and conceptus Tr cells in contact with OPN-coated beads revealed functional integrin activation and cytoskeletal reorganization in response to OPN binding. These results provide a physiological framework for the role of OPN, a potential mediator of implantation in sheep, as a bridge between integrin heterodimers expressed by Tr and uterine LE responsible for adhesion for initial conceptus attachment.
- SourceAvailable from: Qian-Rong Qi[Show abstract] [Hide abstract]
ABSTRACT: Embryo implantation into the maternal uterus is a decisive step for successful mammalian pregnancy. Osteopontin (OPN) is a member of the small integrin-binding ligand N-linked glycoprotein family and participates in cell adhesion and invasion. In this study, we showed that Opn mRNA levels are up-regulated in the mouse uterus on day 4 and at the implantation sites on days 5 and 8 of pregnancy. Immunohistochemistry localized the OPN protein to the glandular epithelium on day 4 and to the decidual zone on day 8 of pregnancy. OPN mRNA and proteins are induced by in vivo and in vitro decidualization. OPN expression in the endometrial stromal cells is regulated by progesterone, a key regulator during decidualization. As a secreted protein, the protein level of OPN in the uterine cavity is enriched on day 4, and in vitro embryo culturing has indicated that OPN can facilitate blastocyst hatching and adhesion. Knockdown of OPN attenuates the adhesion and invasion of blastocysts in mouse endometrial stromal cells by suppressing the expression and enzymatic activity of matrix metalloproteinase-9 in the trophoblast. Our data indicated that OPN expression in the mouse uterus during early pregnancy is essential for blastocyst hatching and adhesion and that the knockdown of OPN in mouse endometrial stroma cells could lead to a restrained in vitro trophoblast invasion.PLoS ONE 08/2014; 9(8):e104955. · 3.53 Impact Factor
Article: Pig blastocyst-uterine interactions.[Show abstract] [Hide abstract]
ABSTRACT: The litter-bearing pig is an invaluable model for research in reproductive biology. Spherical pig blastocysts on Day 10 of pregnancy undergo rapid morphological changes to tubular and then filamentous forms by Day 12 and a filamentous conceptus of almost 1m in length by Day 16 of pregnancy. Thus, trophectoderm of each conceptus achieves intimate contact with luminal uterine epithelium (LE) for exchange of nutrients, gases, hormones, growth factors and other key molecules for survival and development. Estrogens secreted between Days 11 and 13 of pregnancy signals pregnancy recognition to ensure that nutrients and prostaglandin F2-alpha (PGF) are secreted into the uterine lumen (exocrine secretion) rather than into the uterine vein (endocrine secretion) which would lead to regression of the corpora lutea (CL) and failure to maintain pregnancy. Pigs have a true epitheliochorial placenta. The fluid filled amnion bouys the embryo so that it develops symmetrically. The allantois fills with allantoic fluid to expand contact of the chorioallantois with uterine LE, and the allanotois supports the vascular system of the placenta. The chorion/trophectoderm in direct contact with uterine LE exchanges gases and nutrients and forms unique structures call areolae that absorb nutrient-rich secretions from uterine glands and transports them directly into fetal blood. The period from Days 20 to 70 of pregnancy is for placental growth in preparation for rapid fetal growth between Days 70 and 114 (term) of gestation. Maturation of the fetal hypothalamic-pituitary-adrenal axis leads to increases in secretion of cortisol from the fetal adrenal glands. Cortisol sets in motion secretion of estrogens, oxytocin, relaxin and prolactin, as well as increases in their receptors, which are required for delivery of piglets and for initiation of lactation and expression of maternal behavior. This review provides details of gestation in the pig with respect to uterine biology, implantation, placentation, fetal development and parturition.Differentiation 01/2014; · 2.84 Impact Factor
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ABSTRACT: Mucin (MUC) 1 is an inducible innate immune effector, an important component of defense against bacterial invasion, and is linked with infertility in humans. The objectives were to evaluate mRNA expression of MUC1 and cytokine genes in the endometrium of cows with various postpartum uterine inflammatory conditions or with a history of repeat breeding. Endometrial samples were collected from lactating dairy cows diagnosed with metritis (n=4), endometritis (n=4), subclinical endometritis (n=4), or no uterine pathology (normal; n=4). In addition, endometrial samples were collected from repeat breeder cows with (n=4) or without (n=4) subclinical endometritis, as well as unaffected cows (n=4). Quantitative PCR was used to determine mRNA abundances of MUC1, Toll-like receptor (TLR) 4, Interleukin (IL) β1, IL6, IL8, Tumor Necrosis Factor (TNF)α, Insulin-Like Growth Factor (IGF) 1, and IGF binding protein (BP) 2. The mRNA expressions were significantly greater for cows with metritis and clinical endometritis compared to cows with no uterine inflammation, except for IL6. However, mRNA expressions for these target genes were not different for cows with subclinical endometritis, compared to cows without uterine inflammation, except for IL1β and TNFα mRNA (P<0.01). All mRNA expressions were greater (P<0.001) for repeat breeder cows with subclinical endometritis compared to normal cows. However, in repeat breeder cows without subclinical endometritis, only expressions of MUC1, IGF1 and IGFBP2 were greater compared to normal cows (P<0.01). Based on functional protein networks, there were significant associations between these transcripts. In conclusion, endometrial expressions of MUC1 and cytokines genes differed among normal, fertile versus diseased, and subfertile dairy cows. Perhaps these altered gene expressions contribute to endometrial insufficiency and consequently pregnancy wastage.Theriogenology 04/2014; · 1.85 Impact Factor